环氧树脂／聚氨酯梯度聚合物的弯曲性能研究

考察了不同层数的环氧树脂/聚氨酯(EP/PU)梯度聚合物弯曲性能,采用有限元法分析了材料在弯曲状态下的应力分布,从理论上解释了EP/PU梯度材料弯曲性能的试验结果,并与相同组成的均质材料进行了比较.研究发现:EP/PU梯度材料的弯曲强度和模量随梯度层数的增加而增加,当梯度层数超过5层以后,EP/PU梯度材料的弯曲强度高于相同组成的均质材料.有限元分析结果表明:在EP/PU梯度材料中,应力的分布与各层材料承受的强度相匹配,即应力大的部位材料的强度也越大.梯度层越多,各层之间强度变化越小,应力变化越为缓和,且应力分布与材料强度之间匹配越好,在受外力时,材料断裂强度越高.梯度材料中应力分布方式的理论计算结果很好的解释了实测的各种梯度材料强度变化规律.     

一种高性能环氧树脂固化体系的研究

通过凝胶化测试和示差扫描量热分析（DSC）,研究了CYD128／DMP-30体系固化反应性,20℃凝胶化时间为70min;测试了浇铸体力学性能和耐热性,其中拉伸强度为50．2MPa,拉伸模量为3．5GPa,弯曲强度为156．7MPa,冲击强度为15．0（kJ·m^-2,玻璃化温度（Tg）为96℃。研究了连续纤维增强CYD128／DMP-30体系复合材料的性能,其中连续玻璃纤维增强复合材料弯曲强度为954．8MPa,连续碳纤维增强复合材料弯曲强度为1057．4MPa。     

微波固化环氧树脂/苯酚封端的聚氨酯预聚体系的热膨胀行为研究

以二苯甲烷二胺(DDM)为交联剂，研究了环氧树脂／苯酚封端的聚氨酯(EP／PU)预聚体系在微波固化条件下的热膨胀行为；并通过热膨胀行为考察了体系热膨胀系数、玻璃化转变及其与微波功率、体系组成之间的关系。结果表明：当体系组成一定时，随着微波功率的增加，体系中富EP相和富PU相的玻璃化转变移向高温，过渡相的转变加宽，膨胀系数变小。在一定组成范围内，体系具有两个玻璃化转变，随着PU和EP含量的接近，富EP相和富PU相的玻璃化转变温度差值缩小。组成相同的体系，微波固化产品的热膨胀系数低于热固化。     

环氧树脂室温固化体系的研制及性能研究

以兼具引发剂和稀释剂功能的自制BH-1为固化剂,通过引入低黏度活性稀释剂,制备室温固化EP(环氧树脂)胶粘剂;然后以EP/BH-1/活性稀释剂为基体、单向玻璃纤维为增强材料,制备相应的复合材料。研究结果表明:当w(BH-1)=4%时,EP浇铸体的室温(25℃)凝胶时间约为8.5 h和玻璃化转变温度(Tg)为130.9℃,并具有优异的力学性能,其冲击强度为50.0 kJ/m2、拉伸强度和模量分别为0.075 GPa和2.80 GPa、弯曲强度和模量分别为0.136 GPa和3.02 GPa;当m(EP)∶m(BH-1)∶m(活性稀释剂)=100∶4∶10时,复合材料的弯曲强度(0.984 GPa)和层间剪切强度(56.1 MPa)分别提高了26.4%和15.2%。     

梯度层数对聚氨酯／环氧梯度互穿网络聚合物力学性能的影响

设计了一种新的梯度组分分布数学模型，采用梯度因子和梯度层数控制梯度组分的分布，并采用逐层浇铸的方法制备了不同层数的EP／PU梯度互穿网络聚合物（IPN）材料；测试了材料的拉伸性能、弯曲性能以及冲击性能；研究了梯度层数变化对这些性能的影响，并同普通IPN的性能进行了对比。研究结果表明，在相同质量比和梯度因子情况下，梯度层数越多，拉伸强度和冲击强度越高，弯曲强度越低。梯度IPN的拉伸强度和冲击强度均高于普通IPN，弯曲强度低于普通IPN。     

炭黑对酸酐固化环氧体系的反应及性能影响

利用填充混合法制备了环氧树脂（EP）／炭黑（CB）复合材料，研究了CB对体系反应及性能的影响。使用扫描电镜对拉伸断口形貌进行了观察；利用透射电镜观察了CB在EP中的分散状态。结果表明：CB的加入使体系固化时的最高放热温度从179℃降到169℃，凝胶化时间变短；适量CB的引入提高了材料的拉仲强度、断裂伸长率和冲击强度，CB用量在2％时材料的综合力学性能最佳；随着CB用量的增加，复合材料的玻璃化温度也随之提高。     

一种新型叠氮含能固化剂的合成及性能

为提高黏合剂体系的力学性能，通过叠氮聚醚多元醇与六亚甲基二异氰酸酯（HDI）反应合成了一种新型叠氮多异氰酸酯含能固化剂（EC）。研究了料比、反应温度、后处理方法等因素对反应的影响。DSC结果表明，EC的最大热分解温度为252．89℃，玻璃化温度为-47．13℃。EC／GAP胶片的最大热分解温度为254．56℃，玻璃化温度为-45．78℃。EC／GAP／50％TEGDN体系具有良好的物理和化学相容性，制备的胶片有两个分解放热峰，对应的最大热分解温度分别为213．05℃和250．89℃，玻璃化温度为-69．08℃。GAP／EC胶片在＋20℃下的拉伸强度和断裂伸长率分别为0．67MPa和129％，优于GAP／N100体系的0．53MPa和56．5％。     

聚氨酯对环氧树脂改性沥青及混合料性能影响研究

为研究不同用量（20%、30%、40%）聚氨酯（PU）对于环氧树脂（EP）改性沥青及其混合料性能的影响,通过拉伸试验、动态剪切流变和低温弯曲流变试验分析了PU/EP复合改性沥青性能,并利用车辙试验、低温弯曲试验和浸水马歇尔、冻融劈裂试验探讨了复合改性沥青混合料的高温稳定性、低温抗裂性和水稳定性,并以不掺PU的环氧沥青和4%SBS改性沥青混合料为对照组。试验结果表明,加入PU将会降低改性沥青的抗拉强度、车辙因子,但同时提高了沥青的柔韧性和低温性能;加入一定量的PU虽然降低了沥青混合料的高温抗车辙变形能力,但依然远大于4%SBS改性沥青混合料,此外PU加入后明显改善了沥青混合料的低温抗裂性和抗水损害性能。综合各方面性能,建议PU用量为30%～40%。     

聚甲基三乙氧基硅烷改性环氧树脂的研究

采用聚甲基三乙氧基硅烷（PTS）化学改性双酚A型环氧树脂，制备出一系列高性能的PTS改性环氧树脂。对固化物的玻璃化转变温度（Tg）、拉伸强度及断裂伸长率、热稳定性进行了分析测定，探讨了改性方法、有机硅含量等对材料性能的影响。结果表明，双酚A型环氧树脂通过PTS（质量比为100／1B）化学反应改性后：拉伸强度达到56．61MPa，断裂伸长率达到10．40％，Tg达到168．07℃，50％的质量热损失温度达到484℃；比未改性的纯环氧树脂分别提高了7．67MPa、3．66％、15．44℃、36℃。     

PEEK/PEI共混物的相容性和结晶行为研究

在380℃下熔融挤出制得聚醚醚酮（PEEK）与聚醚酰亚胺（PEI）共混物。采用差示扫描量热仪（DSC）和广角X射线衍射仪（WAXD）研究了共混物的相容性和结晶行为。结果表明，PEEK／PEI共混物完全相容．所有共混物均呈现一个玻璃化转变温度（Tg），且与组分的关系符合Porch方程；随PEI含量的增加，共混体系的熔点、结晶度、整体结晶速率和结晶能力均降低：而PEEK的结晶度呈现先增加后减小的趋势，当PEI质量分数为50％时，达到最大。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.